Lotus-type porous metals with low thermal conductivity are fabricated by continuous
zone melting technique, which possess directional elongated pores. The porous metals have been
able to be fabricated through the conventional casting method by utilizing the solubility gap
between solid and liquid in pressurized gas atmosphere. However, there is a shortcoming that the
pores are coarsened in the part farther from the chill plate in the ingot. In order to overcome such a
shortcoming, we developed the continuous zone melting technique and successfully produced the
lotus-type porous metals with even low thermal conductivity such as stainless steel and superalloys.
Furthermore, from the viewpoint of mass production with low cost, we invented novel ”continuous
casting technique”. The molten metals dissolving gas are solidified continuously by passing through
the mold cooled with chiller and thus, lotus-type porous metal plate as long as one meter was
produced for short time. Sufficient uniformity of the porosity and pore size was obtained in such
long porous ingots. This technique is prospective method for commercial mass production.